Setting back plans to shield the nation from a potential bird flu pandemic, the first study of a human vaccine showed that even a massive dose failed to protect nearly half of those inoculated, according to a study released today.
The vaccine for the avian flu strain known as H5N1 was far less effective than the standard seasonal flu vaccine, which protects 70% to 90% of the people who get the shot, according to the study in the New England Journal of Medicine.
The experimental bird flu vaccine required 12 times the dose of the seasonal inoculation. That in effect would cut down the nation's stockpile of the vaccine, purchased for about $160 million, to approximately 4 million courses -- enough to inoculate only some healthcare and vaccine workers.
The current pandemic flu plan, issued by the U.S. Department of Health and Human Services in November, calls for enough vaccine for 20 million people, though it does not set a timetable for acquiring the shots.
"It's disappointing in that it takes so much," said Robert Webster, a virologist at St. Jude Children's Research Hospital in Memphis, Tenn., who has been studying this particular strain of bird flu since it emerged in 1997. "We have to ... find ways to do better, to get more bang for the buck."
Dr. Anthony Fauci, who heads the National Institute of Allergy and Infectious Diseases, acknowledged that the current vaccine "cannot be the answer to where we want to be." He said, however, that the study did demonstrate that the vaccine was partially effective and safe to use.
"It's a bit of muted good news in that we're going in the right direction, but the sobering news is we have a long way to go," he said.
Developing a human vaccine for bird flu has been the cornerstone of the nation's efforts to deal with a potential pandemic.
The virus, which originated in Asia, rarely infects people, but scientists fear a mutation could make it more easily transmissible, sparking a pandemic.
Since 2003, the World Health Organization has recorded only 186 human cases. But H5N1 is clearly lethal: 105 of those people died.
In the last two months, the virus has been detected in birds in Europe, Africa and the Middle East.
Experts believe it could arrive in North America as early as this summer, carried by migrating birds into Alaska or northeastern Canada.
The Department of Health and Human Services has funded studies of more than 30 candidate vaccines. Results from some of these studies are expected to appear in the next six to 12 months.
